Attached plot is the Altair profile from the latest run.
The data don’t go quite as deep as Menkab, but are highly
interesting all the same.
for the IR, V and VE2 filters, the slope is very close
to our canonical r^-3 or so which we get for the moon.
it was a very clear night, so that’s SUPER!
for the B and VE1 filters the halo is rather different — as
can be see in the plot!
we might have some sky subtraction problem with VE2, so let’s
not worry about that too much at this point.
the peculiar profile is definitely B — as before with Menkab —
there is a peculiar hump in the psf at log(r) ~ 0.8 to 1.0
(6 to 10 pixels). We saw the same in Menkab and wondered
Could there be something funny going in with internal
reflections in the B filter, so that an extra halo appears around
stars in that filter but not in the others — or at least not